The present invention relates to a method of forming a coiled wire in an annular groove formed on an inner surface of a cylindrical member.
Conventionally, in order to form a coiled wire in an annular groove formed on an inner surface of a cylindrical core, a forming method is employed as shown in FIG. 1. In the known forming method, a wire is preliminarily wound outside a core 22 and formed into a coil 21 by self-fusion, etc. The coil 21 is inserted into the core 22 by deforming the coil 21 so as to reduce diameter of the coil 21. Then, the coil 21 is again formed in an annular groove 23 of the core 22.
However, the known forming method undesirably needs many steps such as winding, forming, deforming, inserting and re-forming steps. Furthermore, the known forming method has such a drawback that it is difficult to deform the coil so as to properly set the coil in the annular groove, thereby frequently resulting in improper deformation of the coil.
Meanwhile, in Japanese Pat. Laid-Open Publication No. 100911/1986, the assignee assigned by the present inventors proposed a method in which bonding agent is applied to a bottom face of an annular groove and a wire is drawn from a feed nozzle so as to be delivered to the annular groove and wound in the annular groove such that the wire is bonded to the bottom face of the annular groove by a pressing roller disposed downstream in a rotational direction of the feed nozzle.
Thus, in this prior art method in which the wire is fixed to the annular groove by bonding agent while being wound, such advantages can be achieved that since the wire is directly wound in the annular groove, the number of necessary steps can be lessened and the wire can be positively set in the annular groove. However, in this prior art method, if bonding agent has adhered to the pressing roller, the pressing roller may detach the wound wire from the annular groove on the contrary. Furthermore, the prior art method has such a disadvantage that processing of end portions of the coiled wire is required to be separately performed after curing of bonding agent, which is troublesome.